public class Email implements Cloneable{
    private Attachment attachment=null;
    public Email(){
        this.attachment=new Attachment();
    }
    public Object clone(){
        Email clone=null;
        try{
            clone=(Email)super.clone();
        }catch(Exception e){
            System.out.println("Clone failure!");
        }
        return clone;
    }
    public Attachment getAttachment(){
        return this.attachment;
    }
    public void display(){
        System.out.println("查看邮件");
    }
}